The image biomarker standardization initiative: Standardized convolutional filters for reproducible radiomics and enhanced clinical insights

Standardizing convolutional filters that enhance specific structures and patterns in medical imaging enables reproducible radiomics analyses, improving consistency and reliability for enhanced clinical insights. Filters are commonly used to enhance specific structures and patterns in images, such as vessels or peritumoral regions, to enable clinical insights beyond the visible image using radiomics. However, their lack of standardization restricts reproducibility and clinical translation of radiomics decision support tools. In this special report, teams of researchers who developed radiomics software participated in a three-phase study (September 2020 to December 2022) to establish a standardized set of filters. The first two phases focused on finding reference filtered images and reference feature values for commonly used convolutional filters: mean, Laplacian of Gaussian, Laws and Gabor kernels, separable and nonseparable wavelets (including decomposed forms), and Riesz transformations. In the first phase, 15 teams used digital phantoms to establish 33 reference filtered images of 36 filter configurations. In phase 2, 11 teams used a chest CT image to derive reference values for 323 of 396 features computed from filtered images using 22 filter and image processing configurations. Reference filtered images and feature values for Riesz transformations were not established. Reproducibility of standardized convolutional filters was validated on a public data set of multimodal imaging (CT, fluorodeoxyglucose PET, and T1-weighted MRI) in 51 patients with soft-tissue sarcoma. At validation, reproducibility of 486 features computed from filtered images using nine configurations × three imaging modalities was assessed using the lower bounds of 95% CIs of intraclass correlation coefficients. Out of 486 features, 458 were found to be reproducible across nine teams with lower bounds of 95% CIs of intraclass correlation coefficients greater than 0.75. In conclusion, eight filter types were standardized with reference filtered images and reference feature values for verifying and calibrating radiomics software packages. A web-based tool is available for compliance checking

Alterations in JAK /STAT signaling pathway and blood -brain barrier function: Mechanisms underlying worsened outcome following stroke in the aged rat

Effective interventions and therapeutic strategies for stroke victims are few. Investigative focus on the discovery of neuroprotective drugs has drawn attention from gaining a deeper understanding of stroke pathophysiology and mechanisms underlying ultimate neuronal and functional loss. In this study we have described a method for improving the precision and accuracy of clot placement within the middle cerebral artery (MCA) of rats, creating thromboembolic method of occlusion relevant to the majority of strokes seen clinically and included the use of aged animals. We evaluated the pathologic and physiologic differences of stroke in young, adult and elderly female rats, demonstrating an association between animal age and the degree of resultant neuronal damage and functional deficit. The response of supporting cells and structures to ischemia, upon which neuronal survival is critically dependent, is essential in our attempt to reduce severity of acute brain damage. We have examined the role of blood-brain barrier function in stroke progression, demonstrating that aged rats suffer larger infarcts with increased BBB disruption, greater neuronal damage, and reduced functional recovery. Moreover, BBB disruption in the absence of significant neuronal damage suggests a potential mechanism by which alteration in BBB integrity, during stroke, contributes to a greater degree of subsequent neuronal injury. Finally we have examined signaling pathways implicated in cellular response to ischemic injury in young and aged animals. Activation of the janus kinase (JAK) and signal transduction and activator of transcription pathway is rapid following stroke, and the reponse was attenuated in the aged brain. Our data demonstrate early activation of the JAK/STAT signal during stroke in all animals. The phosphorylation of STAT3 in young animals persists, while it is absent in aged animals by 72h post-occlusion. As STAT3 phosphrylation/activation has been demonstrated to promote survival mechanisms, this could unlerlie the inability of aged animals to compensate for neuronal insult. These data emphasize the need for inclusion of aged animals in preclinical evaluation of potential stroke therapies. An accurate MCAO model, which mimics the stroke population and allows for effective, reliable reperfusion, is imperative for the successful translation of therapeutic strategies and improved stroke outcomes in elderly patients

Obesity Is Not Associated With Postoperative Complications After Vestibular Schwannoma Surgery in a Large Single Institution Series.

OBJECTIVE: Determine whether elevated body mass index (BMI) is associated with postoperative complications after vestibular schwannoma (VS) surgery. STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center. PATIENTS: Two hundred six patients undergoing surgery for VS between 2010 and 2017, grouped into obese and nonobese patients. INTERVENTION: Surgery for VS resection. MAIN OUTCOME MEASURES: Postoperative facial nerve outcomes, length of hospital stay, presence of postoperative cerebrospinal fluid leak, 30-day readmission, return to the operating room, wound complications, cardiovascular and thromboembolic complications. RESULTS: After excluding 1 patient for missing BMI, our cohort included 205 patients. Seventy-nine patients (38.5%) were obese (mean BMI 36.2 kg/m, range 30-55.1) and the remaining 126 (61.5%) were nonobese (mean BMI 25.0, range 18.8-29.8 kg/m). Compared with nonobese patients, obesity was not associated with postoperative cerebrospinal fluid leak (OR 1.1, 95% CI 0.93-1.1), length of hospital stay (OR 0.98, 95% CI 0.65-1.47), 30-day readmission rates (1.04, 95% CI 0.95-1.14), return to operating room (OR 1.05, 95% CI 0.98-1.11), or other wound-related complications (OR 0.99, 95% CI 0.94-1.04). CONCLUSION: In this cohort, elevated BMI was not associated with an increased risk for postoperative complications after VS surgery. Our findings may mitigate concerns associated with surgical management of VS in obese patients

Middle Fossa Approach for Resection of Vestibular Schwannomas: A Decade of Experience.

BACKGROUND: The middle cranial fossa (MCF) approach is a challenging surgical technique for the resection of small and intermediate sized, primarily intracanalicular, vestibular schwannomas (VS), with the goal of hearing preservation (HP). OBJECTIVE: To describe a decade-long, single institutional experience with the MCF approach for resection of VS. METHODS: This is a retrospective cohort study of 63 patients who underwent the MCF approach for resection of VS from 2006 to 2016. Audiometric data included pure-tone average (PTA), low-tone pure-tone average (LtPTA), word recognition score, and American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) hearing classification at presentation and follow-up. Patients with postoperative serviceable (AAO-HNS class A-B) and/or useful (AAO-HNS class A-C) hearing were compared to those without HP. Facial nerve function was assessed using the House-Brackmann scale. RESULTS: The mean age and duration of follow-up were 50 ± 13 yr and 21 ± 21 mo, respectively. The mean tumor size was 10 ± 4 mm. The serviceable and usable HP rates were 54% and 50%, respectively. Some residual hearing was preserved in 71% of patients. Large tumor size (P = .05), volume (P = .03), and extrameatal tumor extension (P = .03) were associated with poor audiometric outcomes. The presence of a fundal fluid cap (P = .01) was a favorable finding. At definitive testing, LtPTA was significantly better preserved than traditional PTA (P = .01). Facial nerve outcomes, tumor control rates, and durability of audiometric outcomes were excellent. 47% of patients pursued aural rehabilitation. CONCLUSION: In our series, the MCF approach for VS provided excellent rates of tumor and facial nerve function, with durable serviceable HP

Phase II North Central Cancer Treatment Group study of 2-cholorodeoxyadenosine in patients with recurrent glioma.

There is no standard treatment for patients with recurrent gliomas, and their prognosis remains poor. 2-Chlorodeoxyadenosine is a purine analogue that has significant activity in many low-grade lymphoproliferative disorders. The authors conducted a phase II study to determine the efficacy of 2-chlorodeoxyadenosine in patients with recurrent gliomas. Patients with a histologically confirmed primary brain tumor with evidence of progression after radiation therapy were eligible. Protocol treatment consisted of 2-chlorodeoxyadenosine 7.0 mg/m2 intravenously on days 1 through 5 every 28 days. For those with a history of prior nitrosourea therapy, the dose of 2-chlorodeoxyadenosine was reduced to 5.6 mg/m2 on days 1 through 5. Treatment was continued until progression or a maximum of 12 cycles. Fifteen patients with recurrent astrocytomas or oligoastrocytomas of all grades were entered in the study. Treatment was well tolerated. Major toxicities were myelosuppression and neurotoxicity. No responses were seen. The authors conclude that although 2-chlorodeoxyadenosine is well tolerated, no demonstrable activity in patients with recurrent gliomas was established

The Image Biomarker Standardization Initiative: Standardized Quantitative Radiomics for High-Throughput Image-based Phenotyping

Background Radiomic features may quantify characteristics present in medical imaging. However, the lack of standardized definitions and validated reference values have hampered clinical use. Purpose To standardize a set of 174 radiomic features. Materials and Methods Radiomic features were assessed in three phases. In phase I, 487 features were derived from the basic set of 174 features. Twenty-five research teams with unique radiomics software implementations computed feature values directly from a digital phantom, without any additional image processing. In phase II, 15 teams computed values for 1347 derived features using a CT image of a patient with lung cancer and predefined image processing configurations. In both phases, consensus among the teams on the validity of tentative reference values was measured through the frequency of the modal value and classified as follows: less than three matches, weak; three to five matches, moderate; six to nine matches, strong; 10 or more matches, very strong. In the final phase (phase III), a public data set of multimodality images (CT, fluorine 18 fluorodeoxyglucose PET, and T1-weighted MRI) from 51 patients with soft-tissue sarcoma was used to prospectively assess reproducibility of standardized features. Results Consensus on reference values was initially weak for 232 of 302 features (76.8%) at phase I and 703 of 1075 features (65.4%) at phase II. At the final iteration, weak consensus remained for only two of 487 features (0.4%) at phase I and 19 of 1347 features (1.4%) at phase II. Strong or better consensus was achieved for 463 of 487 features (95.1%) at phase I and 1220 of 1347 features (90.6%) at phase II. Overall, 169 of 174 features were standardized in the first two phases. In the final validation phase (phase III), most of the 169 standardized features could be excellently reproduced (166 with CT; 164 with PET; and 164 with MRI). Conclusion A set of 169 radiomics features was standardized, which enabled verification and calibration of different radiomics software. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Kuhl and Truhn in this issue

The Image Biomarker Standardization Initiative:Standardized Quantitative Radiomics for High-Throughput Image-based Phenotyping

Background: Radiomic features may quantify characteristics present in medical imaging. However, the lack of standardized definitions and validated reference values have hampered clinical use. Purpose: To standardize a set of 174 radiomic features. Materials and Methods: Radiomic features were assessed in three phases. In phase I, 487 features were derived from the basic set of 174 features. Twenty-five research teams with unique radiomics software implementations computed feature values directly from a digital phantom, without any additional image processing. In phase II, 15 teams computed values for 1347 derived features using a CT image of a patient with lung cancer and predefined image processing configurations. In both phases, consensus among the teams on the validity of tentative reference values was measured through the frequency of the modal value and classified as follows: less than three matches, weak; three to five matches, moderate; six to nine matches, strong; 10 or more matches, very strong. In the final phase (phase III), a public data set of multimodality images (CT, fluorine 18 fluorodeoxyglucose PET, and T1-weighted MRI) from 51 patients with soft-tissue sarcoma was used to prospectively assess reproducibility of standardized features. Results: Consensus on reference values was initially weak for 232 of 302 features (76.8%) at phase I and 703 of 1075 features (65.4%) at phase II. At the final iteration, weak consensus remained for only two of 487 features (0.4%) at phase I and 19 of 1347 features (1.4%) at phase II. Strong or better consensus was achieved for 463 of 487 features (95.1%) at phase I and 1220 of 1347 features (90.6%) at phase II. Overall, 169 of 174 features were standardized in the first two phases. In the final validation phase (phase III), most of the 169 standardized features could be excellently reproduced (166 with CT; 164 with PET; and 164 with MRI). Conclusion: A set of 169 radiomics features was standardized, which enabled verification and calibration of different radiomics software